摘要： This paper presents the design of a high gain low profile antenna array for Ka band airborne and space borne SAR systems. The antenna array, with a dimensions of 454×58.8×12.4mm3, is divided into a number of small linear sub arrays, and a low loss waveguide feed network, with a dimension of 360.5×48.6×6.2mm3 is designed to combined all these sub arrays to form a fixed beam antenna. The antenna array adopts metal waveguide slot antenna as the element where the slots are open in the narrow side. The slots in the array are designed to fed with equal magnitude and equal phase, and the size of the slots as well as the sub array are all optimized to have a well impedance matching while a high gain at the same time. What’s more, a groove is added at the side of the array to further enhance the radiation. The simulated maximum gain of the antenna array is 34.1dBi at the central frequency and the VSWR is less than 2 in a bandwidth of more than 0.5GHz, indicating that the designed antenna array is a good candidate for future Ka band SAR systems.